We propose to study the interactions of proteins and lipids using a model system, cyclopropane fatty acid (CFA) synthetase. The substrates for this enzyme are S-adenosyl methionine and the mono-unsaturated fatty acyl moiety of a phospholipid molecule in a lipid vesicle. This enzyme therefore provides a model for a specific protein-lipid interaction. The main method to be used to study the interactions of the purified enzyme with lipids in 13C nuclear magnetic resonance. BIBLIOGRAPHIC REFERENCES: W.D. Nunn and J.E. Cronan, Jr. (1976) Host Membrane Lipid Synthesis is Not Required for Successful Phage T4 Infection. Virology 69: 332-335. T.K. Ray, J.E. Cronan, Jr. and G.N. Godson (1976) The Specific Inhibition of Phospholipid Synthesis in plsA Mutants of Escherichia coli. J. Bacteriol. 125: 136-141.